Study On The Law Of Fault Activation Under The Influence Of Horizontal Stress

Fault is a common special geological structure in the process of coal mining,which cuts the continuity and integrity of coal strata.Under the influence of mining disturbance in working face,it is easy to activate and easily induce rock burst.It poses a great threat to the safety and equipment of underground workers and is not conducive to the sustainable development of coal mine economy.At present,the influence of horizontal stress on fault activation relationship has not attracted academic attention.Therefore,based on the fault geological data of 7303 working face in Xinglongzhuang Coal Mine,the influence of horizontal stress on fault activation is put forward in this paper,and the research methods such as similar material simulation,numerical simulation and on-site micro-seismic data monitoring are carried out in-depth study.The main research results are as follows:(1)Based on the research results of many scholars at home and abroad,two methods,micro statistics and macro mechanics,are put forward to analyze fault activation:?the constitutive equation of fault rock medium is constructed by means of Weibull distribution density and micro-statistics and macro-mechanical analysis.The stress-strain law of rock medium is observed to analyze the micro-failure of fault rock medium.? the plane mechanical model of fault plane is constructed and the ultimate shear stress of fault plane is calculated according to Coulomb's law of friction to determine whether the ultimate shear stress of fault plane reaches the slip condition.Determine if the fault is activated.(2)Based on the hinge equilibrium theory of basic roof fracture block,the influence of different mining sequence and different horizontal stress on the activation of fault in mining process on both sides of fault is analyzed.When the upper plate is mined to the fault,the load of the basic roof block can be transferred to the opposite plate most of which is easy to form stable structure.However,when the dip angle of the fault is less than 52°,it is not easy to form the structure in the lower direction fault mining.Therefore,the risk of fault activation in the lower face is greater than that in the upper face.It is found that the greater the initial horizontal stress is,the less the fault activation degree is.(3)By means of similar materials and numerical simulation,the activation law of fault-oriented fault under different horizontal stresses is analyzed in detail.It is found that the larger the initial horizontal stress is,the less the overall motion amplitude and fault slip amount of overlying strata are,the weaker the sensitivity of stress variation law of fault plane is,and the lower the risk of fault activation.(4)By adjusting the SOS micro-seismic monitoring data of Xinglongzhuang Coal Mine,Baodian Coal Mine and Dongtan Coal Mine,it is found that the higher the initial horizontal stress is under the same geological conditions.The fault micro-earthquake events and the energy of micro-earthquakes decrease obviously,that is,the fault activation risk decreases.Theoretical analysis,similar materials and numerical simulation results are consistent,and verify the effectiveness of the research results in this paper.The results of this study have some guiding significance for the stress behavior of roof near fault and the special geological ore pressure law,and some technical methods have been put forward.